LED driver for VLC

Patent metadata

Field	Value
Publication number	US-11075696-B2
Application number	US-201816482961-A
Country	US
Kind code	B2
Filing date	Feb 8, 2018
Priority date	Feb 8, 2017
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

An LED driver for driving a plurality of LEDs or LED groups to transmit light in a VLC mode is described, wherein the LED driver comprises a control unit that is configured to:
receive, at an input terminal, a set-point representing a desired illumination characteristic and data that is to be transmitted using VLC; determine a current profile for each of the plurality of LEDs or LED groups to generate the desired illumination characteristic, whereby an envelope of the combined current profile comprises a modulation in order for a corresponding intensity modulation as perceived by a sensor to represent a variable length VLC code representing the data, the VLC code comprising code words, a code word comprising a plurality of symbols; generate one or more control signals to drive the plurality of LEDs in accordance with the current profiles in order for the plurality of LEDs or LED groups to transmit the VLC code; and upon receipt of a further set-point representing a different illumination characteristic during the transmission of the VLC code, determine an adjusted current profile or profiles for one or more of the plurality of LEDs or LED groups based on the different illumination characteristic, whereby the current profile is only adjusted for some, not all, symbols of a next code word to be transmitted; generate one or more control signals to drive the plurality of LEDs or LED groups in accordance with the adjusted current profile or profiles, and output, via an output terminal of the control unit, one or more control signals to drive the plurality of LEDs or LED groups in accordance with the adjusted current profile or profiles.

First claim

The invention claimed is:

1. A visual light communication (VLC) method for a lighting system comprising an LED driver and a plurality of LEDs or LED groups, the method comprising the steps of:
receiving a set-point representing a desired illumination characteristic and data that is to be transmitted using VLC;
determining a current profile for each LED or LED group of the plurality of LEDs or LED groups based on the desired illumination characteristic represented by the set-point, whereby an envelope of a combined current profile of the current profiles is modulated in order for a corresponding intensity variation as perceived by a sensor to represent a variable length VLC code representing the data, the VLC code comprising one or more code words, a code word comprising a plurality of symbols, whereby each of the plurality of symbols is characterized by a respective predetermined period; and
generating one or more control signals to drive the plurality of LEDs or LED groups in accordance with the current profiles in order for the plurality of LEDs or LED groups to transmit the VLC,
wherein the combined current profile has a high current period and a low current period during each predetermined period and wherein the combined current profile comprises, during the high current period or the low current period of at least one of the predetermined periods characterizing a symbol, at least one current increment during a current increment period that is less than the high current period or the low current period.

2. The visual light communication method according to claim 1 , wherein the step of determining a current profile for each of the plurality of LEDs or LED groups comprises determining a modulated current profile for at least one LED or LED group of the plurality of LEDs or LED groups.

3. The visual light communication method according to claim 2 , wherein a modulation of the combined current profile corresponds to a modulation of the modulated current profile for the at least one LED or LED group of the plurality of LEDs or LED groups.

4. The visual light communication method according to claim 1 , wherein the combined current profile comprises a summation of the current profiles of the plurality of LEDs or LED groups.

5. The visual light communication method according to claim 2 , wherein the plurality of LEDs or LED groups comprise LEDs or LED groups having a different color and the at least one LED or LED group of the plurality of LEDs or LED groups is selected based on the data.

6. The visual light communication method according to claim 1 , wherein the data is encoded in the envelope of the combined current profile.

7. The visual light communication method according to claim 1 , wherein the at least one current implement is applied to one or more current profiles.

8. The visual light communication method according to claim 1 , wherein a difference between an average current during the high current portion and an average current during the low current portion is above a predetermined value.

9. The visual light communication method according to claim 1 , wherein a current increment is applied on a subset of the symbols of a code word.

10. The visual light communication method according to claim 1 , wherein a positive current increment is applied on a subset of the symbols and a negative current increment is applied on another subset of the symbols of the code word.

11. The visual light communication method according to claim 1 , wherein the current increment starts at the beginning of a symbol.

12. The visual light communication method according to claim 1 , wherein the current implement is applied symmetrically about a central position of the high current period or the low current period.

13. The visual light communication method according to claim 1 , wherein the high current period proceeds the low current period.

14. The visual light communication method according to claim 1 , wherein a transition between the high current period and the low current period takes longer than a predetermined period.

15. The visual light communication method according to claim 14 , wherein the predetermined period is an incremental period associated with a clock frequency.

16. The visual light communication method according to claim 1 , wherein the current increment corresponds to a minimal period current increment.

17. An LED driver for driving a plurality of LEDs or LED groups to transmit light in a VLC mode, wherein the LED driver comprises a control unit that is configured to perform the method according to claim 1 .

18. A visual light communication (VLC) method for a lighting system comprising an LED driver and a plurality of LEDs or LED groups, the method comprising the steps of:
receiving a set-point representing a desired illumination characteristic and data that is to be transmitted using VLC;
determining a current profile for each LED or LED group of the plurality of LEDs or LED groups based on the desired illumination characteristic represented by the set-point, whereby an envelope of a combined current profile of the current profiles is modulated in order for a corresponding intensity variation as perceived by a sensor to represent a variable length VLC code representing the data, the VLC code comprising one or more code words, a code word comprising a plurality of symbols, whereby each of the plurality of symbols is characterized by a respective predetermined period;
generating one or more control signals to drive the plurality of LEDs or LED groups in accordance with the current profiles in order for the plurality of LEDs or LED groups to transmit the VLC;
receiving a further set-point representing a different desired illumination characteristic;
determining a further current profile for one or more of the plurality of LEDs to generate the different desired illumination characteristic represented by the further set-point; and
determining one or more intermediate current profiles for one or more of the plurality of LEDs, and determining output control signals for the LED driver to sequentially drive the plurality of LEDs or LED groups according to:

the current profiles when transmitting a first code word;
the one or more intermediate current profiles, when transmitting a respective one or more further code words, and
the further current profiles when transmitting a yet further code word.

19. An LED driver for driving a plurality of LEDs or LED groups to transmit light in a VLC mode, wherein the LED driver comprises a control unit that is configured to perform the method according to claim 18 .

20. An LED driver for driving a plurality of LEDs or LED groups to transmit light in a VLC mode, wherein the LED driver comprises a control unit that is configured to:
receive, at an input terminal, a set-point representing a desired illumination characteristic and data that is to be transmitted using VLC;
determine a current profile for each LED or LED group of the plurality of LEDs or LED groups based on the desired illumination characteristic represented by the set-point, whereby an envelope of a combined current profile of the current profiles is modulated in order for a corresponding intensity variation as perceived by a sensor to represent a variable length VLC code representing the data, the VLC code comprising one or more code words, a code word comprising a plurality of symbols, whereby each of the plurality of symbols is characterized by a respective predetermined period; and
generate one or more control signal

Assignees

• Eldolab Holding Bv

Inventors

• Saes Marc
• Otten Andy Johanna Elisabeth

Classifications

• H05B45/10

  Controlling the intensity of the light · CPC title

• H04B10/116 Primary

  Visible light communication · CPC title

• H05B45/20

  Controlling the colour of the light · CPC title